What Are The Basic Parts Of A Bullet? | Ammunition Components

Firearms have been integral to human history for centuries, changing how we conduct war, hunt, sport, and even personal defense. The humble yet intricate bullet is at the heart of the firearm’s operation – a marvel of engineering that harnesses the power of physics and chemistry to deliver precision over great distances.

Understanding the anatomy of a bullet and how it operates is fundamental to appreciating its function and crucial to ensuring consistent hunting results. In this article, we dissect the bullet and analyze its integral parts, we also discuss differences between common types of ammunition. Enjoy the read!

What Are The Basic Parts Of Ammunition?

The basic components of ammunition can be summarized into five main parts, which we discuss below. Remember that different bullet types can often be made from different material and components.

1) Bullet Case

Also known as the casing or shell, this is the container that holds all the ammunition components. The typical cartridge case is made from brass, but you also get steel and aluminum casings. They also come in various sizes like the 223 or 556 rounds that are quite large.

2) Bullet Primer

The primer is a small metal cup containing trace amounts of an impact-sensitive explosive chemical compound. When you pull the trigger, the gun’s firing pin strikes the primer, igniting the explosive, which ignites the gunpowder.

3) Gunpowder

Also known as propellant, gunpowder is a chemical mixture that burns quite rapidly when ignited. This rapid ignition is vital in ensuring successful gunfire, producing a large volume of hot gas. This hot gas, in turn, is used to propel the projectile out of the firing chamber and barrel of the weapon. Modern cartridges use smokeless powder, but you still get black powder compatible cartridges.

4) Projectile

The projectile, commonly referred to as a bullet, is the part of the ammo cartridge fired from the firearm to the intended target. The typical bullet is made from lead with a copper jacket but can also be composed of other metals.

5) Wad

A wad is typically only found in shotgun shells. It is a vital part of the shotgun ammo, as it separates the powder from the shot (a bunch of small projectiles). It also helps seal the gases produced when the powder is ignited, ensuring the gasses all push forward rather than leaking out of the back of the shell.

How Is Shotgun Ammo Different?

Shotgun Bullet Diagram

Shotgun ammo is a little different from a typical rimfire cartridge or centerfire ammunition in a few ways:


Wad: A shotgun contains a wad that separates the gunpowder from the projectiles and seals gasses in the shell.

Shot: A shotgun uses a shot instead of a single bullet. A shot comprises multiple projectiles, typically made from lead or steel. These small projectiles spread out in a pattern, making a shotgun ideal for hitting small, fast-moving targets. However, you get single projectile shells, known as slugs. Typically, you get three main types of shotgun ammo, buckshot (used for hunting game), birdshot (hunting birds), and slug (hunting large game at longer ranges).

Case: Instead of a brass casing, shotgun shells usually have a plastic hull with a metal base containing a primer.


You measure shotgun ammo in gauges instead of calibers like standard ammo. The gauge is correlated to the diameter of the shotgun bore.

The gauge is determined by the weight of a pure lead round ball with the same diameter as the inside of the barrel – a 12-gauge is about .729 inches in diameter.

Comparing Centerfire vs Rimfire Ammunition

The makeup of a cartridge and the design of its components significantly impact its performance, cost, and use cases. In particular, the distinction between centerfire cartridges and rimfire ammunition is one that is interesting and a crucial piece of knowledge for any hunter.

Centerfire Cartridge

A centerfire cartridge is named as such because the primer cap is located in the center of the cartridge case base. When you pull the trigger, the firearm’s firing pin strikes the primer, igniting the propellant. Here are some advantages of centerfire ammunition:

  • More reliable than rimfire ammo
  • Can be salvaged and reloaded for custom loads – a discipline I often practice to optimize my loads and reduce ammo cost.
  • There is a broad spectrum of calibers you can choose from – everything from diminutive handgun rounds to heavy large rifle cartridges.

Rimfire Cartridge

In a rimfire cartridge, the primer is spun into the rim of the case base and cannot be seen from the outside of the cartridge. They also ignite with the help of a firing pin. But instead of hitting the primer directly, the pin punches the rim, setting off the propellant. Rimfire ammo has its own set of benefits:

  • They are cheaper than centerfire cartridges because they are generally less expensive to produce – making them ideal for target practice and plinking.
  • Rimfire cartridges are smaller, like the popular .22 LR and .17 HMR, producing less recoil.
  • Rimfire cartridges are generally quite than centerfire ammunition, making them ideal for varminting small animals.

What Is The Difference Between Rifle & Pistol Ammo?

Although they use the same principle to fire, they differ in several ways, including design, power, and intended use:

  • Bullet Type: Rifle rounds are designed for deeper penetration and to be more aerodynamic. Whereas a pistol bullet is often flat-nosed or round-nosed.
  • Size and Shape: Pistol ammo is typically shorter and wider than its rifle ammo counterpart, which is longer and narrower.
  • Velocity and Power: Rifle ammo can withstand much higher pressures than pistol ammo. Therefore, they can achieve much higher velocities and power than pistol ammo.
  • Recoil: With higher power, unfortunately, comes more recoil – rifle ammo produces more recoil than pistol ammo.
  • Primer: Rifles and pistols use different types of primers.
  • Cost: At your typical gun store, you can expect to pay more for rifle ammo than pistol ammo. This is because rifle ammo requires more propellant and manufacturing materials than pistol ammo.

Parts Of A Bullet Diagram

Below you will find an intuitive diagram of the parts of a bullet. While some bullets can look different, this is the general design manufacturers follow when designing and producing bullets.

Parts of a bullet Diagram

How Does A Bullet Fire?

The following steps occur when a bullet is fired:

  1. A cartridge like the 338 Lapua is chambered, meaning it is inserted into the firearm’s chamber.
  2. The action is closed, and the firing pin is pushed back and held under spring tension.
  3. You pull the trigger, releasing the firing pin, which moves with considerable force.
  4. The firing pin strikes the back of the primer cap and results in a small explosive charge.
  5. Consequently, the spark from the primer ignites the gunpowder.
  6. Gas produced from the burning powder expands quickly in the cartridge.
  7. The expanded gas’s force is so great that it forces the bullet out of the cartridge and down the gun’s barrel.
  8. The unique rifling twist within the barrel causes the bullet to spin – stabilizing it and improving its accuracy.
  9. Finally, the bullet is propelled out of the gun with a loud sound and muzzle report.

Frequently Asked Questions

What makes a bullet more powerful?

Various things can elevate a bullet's power, such as increasing the load used, using different bullets like a jacketed hollow point or other more aerodynamic bullets, and shooting targets at closer range.

Can you refill your own ammunition?

Yes, you can refill certain types of ammunition, specifically centerfire cartridges. However, it is important that you gain the proper knowledge and skills needed to reload ammunition because any error can lead to a dangerous situation where the rifle's barrel can explode.

What type of gunpowder is the best?

There are many brands and types of gunpowder available for cartridges, and different cartridges perform better with certain gunpowders. However, these five gunpowder brands are always good options: Hodgdon Varget Powder, Alliant Reloder 15, IMR 4064 & 4350, Accurate 4350 & 4064, and Vihtavuori N500 series.

Which type of bullet is best for hunters?

The best bullet largely depends on the type of game you are hunting, the environment, and the distance to your shots. However, from experience, the best bullet is the Soft Point (SP) or Jacketed Soft Point (JSP) bullet. Upon impact, they expand (mushroom), causing more damage and delivering higher kinetic energy to the target. They are the best because they have the best balance between power, effectiveness, cost, and availability.

The Bottom Line

There you have it; now you know that the basic parts of ammunition are incredibly intricate. Each component plays a pivotal role in the successful discharge of a bullet. Remember that you get different types of ammunition, each with its own benefits and drawbacks. Also, remember to treat firearms with respect and responsibility, as they are incredibly dangerous to those who use them and the people around them. Whether for hunting, sporting, or defense, having this knowledge allows you to make informed decisions the next time you go ammo shopping.

About the author

Patrick Howard

I have been working as a gunsmith for 20 years. Rain, fog, moisture, high temperature, or even snow are all the things a product must withstand in order to be recommended by me.

Leave a Comment